Fatima's batting average after 19 innings (out every time) is a certain number. In her 20th innings she scores 96 and is out, and her average rises by 3. What is her new average?

36Correct answerYour answer39Correct answerYour answer42Correct answerYour answer93Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer B

Correct answer: B

Let the old average be a. Then $19a + 96 = 20(a + 3)$ .
$19a + 96 = 20a + 60$ , so $a = 36$ .
New average = $36 + 3 = 39$ .

Worth noting

Shortcut: the 96 lifts all 20 innings by 3, so $96 - 20 \times 3 = 36$ is the old average, and the new one is 39. 36 is the OLD average, a common slip.

Concept: Using the rise in batting average to find the old average
Typical timeTypical: 70 s
Your timeYours: —

The rule this testsChange in average

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Ten questions from Averages, at your own pace.

Fatima's batting average after 19 innings (out every time) is a certain number. In her 20th innings she scores 96 and is out, and her average rises by 3. What is her new average?

Explanation